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Reduce your Electric Bill with a Window Air Conditioner

Posted on Jul 29, 2008 by Paul White


Our house is newer ( built in 2005 ).  So of course you would think that maybe it would have newer stuff.  Wiring, Appliances, and most of all a newer AC unit.  Well it turns out that with most newer homes one of the things builders skimp out on is a high efficiency AC unit.  After reading the sticker on ours I found that it was a 10 SEER unit.  The year after our house was build the lowest that could be installed in a new home was raised to 12 SEER by federal law.  Our Utility costs are about 15 cents / KWH.  Last month we went through over 2000 KWH.  I am not sure if Global warming is to blame but one thing I did notice was the average temperature for the month of June was 94 degrees,  compared to 88 degrees last year.  We used 600 KWH more this June than last. 

What is a KWH?

For those of you who don't have a concept of what a KWH is here is an explanation.  Its basically how many 1000 watts you consume in 1 hour.  Lets say you have a 60 watt light bulb. And you leave it on 24 hours a day.  This bulb consumers .06 KWH.  This times how many hours you leave it on will give you your KWH usage. Utility companies charge per KWH.  This rate can vary from 4 cents up to over 25 cents / KWH.  Here in Texas we pay about 15 cents / KWH. 

The Problem

By far the biggest consumer of electricty is your home's Central Air Conditioner.  After doing some research I figured that this was the cause of our high electric bills.  Unlike many, both me and my wife work out of the home.  Since we both work out of the home we don't have the luxury of turning down the AC during the day.  But then the problem is not so much that we have home offices, but it is that I like it to stay around 72 and my wife is comfortable at 75.  My office is towards the front of the house, while hers is at the back.  Now the question is why should I keep 2000 SQFT of house 72 degrees when I only need about 150 SQFT ( my office ) to be comfortable during the day.  After talking with some people, I realized that we could benefit from upgrading our home's Air Conditioning unit, but this would cost around 8K-12K.  This would cut our electric bill in half, but it would take several years to make up the difference.  I also looked at installing solar panels, and or a wind Turbine to make up the difference. But each of these options were more expensive than just upgrading our home's AC unit.

The Solution

The conclusion I came to was that the only solution was to install a dedicated window air conditioner in my office.  I had browsed some stores online to get a feel of the cost.  I found the perfect little unit at Sams Club.  It was a GE 6000 BTU Window unit that cost about $148.  The unit came with a digital display, remote control, and all installation hardware.  The installation was easy.  The unit has a special energy saving mode, to help keep energy usage to a minimum.  It also has more than enough cooling power for my little office.

GE Window Air Conditioner

How much Power does it use?

One of the biggest concerns I had was how much power would it consume?  I used my Kilawatt meter to see.  When the fan is going it uses 50-60 watts.  When the compressor is on it uses 500-650 watts.  I have the meter running on it to track what its total usage is within 24 hours.  This will help me guage how much it will cost me to operate this for the month.  Of course by using this instead of Central Air Conditioning, should save me a bundle.  I estimate this window unit will pay for itself in 1 month.

GE Window Air Conditioner


After tracking the usage for 24 hours. ( 14 hours  on ).  and with my thermostat set to 72, the unit consumed 4.46 KWH.
If we multiple this by 30 days in a month we get 133.8 KWH.  Times my utility rate of 15 cents / KWH = $20.07.
So on average to run this unit in my office 14 hours / day it should cost me about $20 / month.
Killawatt on window Air conditioner

Yesterday I was at Lowes. and I noticed they have a window AC unit for under $100.  It didn't have any of the cool features like energy saver, or digital display or a remote control, but it might get the job done.  If you have a membership at Sams Club, you can't go wrong with the GE brand window air conditioners. 

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mojavi | Aug 30, 2008 10:23 PM
we had the smae problem this year with a rental house. Our electric bill has been 500.00 a month we used 3000 last month!!! I started recording how much the ac used a day and it was 100-90 a day. SO we got two window units. I am anxious to see how much we use by morning. Also the owner refuses to replace the AC unit! ugg
paul | Aug 30, 2008 10:39 PM
mojavi, I hear ya!  Even though our house has a 10 SEER central AC unit ( not very efficient ) our bills were never quite this bad last year.  Last month reliant raised us from 15.4 cents / KWH to 16.9 KWH. Now we are looking to find a new provider as that is just too high to pay.  Here is our current setup for our house.  We still use the central AC but we have the thermostat set at 78 24/7  instead of 72(day) and 68 ( night ).  Then we have installed a window AC unit in both my office and our bedroom.  The AC unit in my office is a 9.8 EER GE unit rated at 6,000 BTU( in the picture ) above.  The one in our bedroom is a 10.8 EER GE unit rated at 8,000 BTU.  During the day I run the office unit and keep it around 72 ( which can almost get too cold at times ).  The bed room unit we run at 68 all night long.  I have been reading our meter daily.  I am now only using 30-37 KWH / day.  At this rate my total monthly usage will be down to 1100 KWH.  I highly recommend anyone who is looking for a way to reduce their energy costs to consider window units.

Sorry to hear about your Landlord not replacing the AC unit.  Even if the owner did replace it, I am willing to bet that a window unit would use less electricity.  Good luck and let me know how it works out for you.  I will be posting my bills for before and after comparisions after my next bill comes in sometime around the 17th of this month.
Shelly | Feb 12, 2009 7:15 PM
If you live in a climate that the temperature at night is pretty cool compared to the day time temperature - try a whole house fan - it will cool the living space and attic space at the same time- I learned that your house stats hot because the attic is hot - I bought one at www.wholehousefan.com - LOVE IT!! saved me about $150.00 a month on my electric ---
Helen | Aug 18, 2010 12:23 PM
We bought 2 window ac units and quit using our central air and yesterday we got our electric bill and it was exactly cut in half.  No more central air for us.
Cindi | Jun 10, 2011 6:22 PM
Love this article!  This is just the kind of info I was looking for!  I just got a window unit for my office because I work at home too.  I live in Texas, and had been keeping my central A/C set on 72 cooling the whole house all day long.  Since I spend most of my time in my office, I now set the thermostat on 78 and use my little 5000 BTU window unit during the day.  It keeps it very comfortable in here.  I can't wait to see how much money this saves me.  I paid $99 dollars for this one at Home Depot.  It doesn't have a remote or a digital display.  I keep the fan on low and the cooling on the 4 or 5 setting. 
john | May 14, 2012 9:58 PM
thanks man....this was exactly what i was looking for. i live with a large household, some not willing to pay to keep the house cold, so i am going to keep my room cold....i love the kilowatt usage meter...i just ordered one from amazon....25 bucks...well worth the tracking ability of my bills....so once again....thanks
Vince | May 28, 2012 4:26 PM
I am a single father, having my daughter 2 days each week. I live in a 60 foot trailer, and was having monthly electric bills of $300 and above each month in the summer. I have moved the television and my recliner into the spare bedroom, and put in a 5000 btu window ac. When my daughter isn't with me, I cool ONLY this room, and use it both as my day time office, and sleep there at night. I can only imagine that this will save me close to $1000 or more this summer alone. The ac unit cost $109.
Mike | Jul 11, 2012 9:43 AM

One of our central air units went out (leaking at the coil drip pan), and it's over $1,000 to replace.  The system only cools our kitchen, familyroom, and on small bathroom, and another room that is used as storage only.  We bought a 8,000BTU unit to keep the family room cooled, and didn't realize it is cooling the entire 600 square feet.  It doesn't run all the time, when in energy efficient mode, and auto.  We have spent up towards $400+/month when running both central air systems, and the house never really cools down.  With the window unit and the other central air system unit (cools living room, 4 bedrooms and full bathroom) the entire house is much more comfortable, even during 90F plus days. We have it set for 80F.  I can't wait to see the savings just from doing this.  I think you have to be foolish to burn money with central air.  A lot of the cooling is wasted anyway.
I love this article and all the feedback.

Home page | Feb 13, 2013 9:06 AM
I definitely agree with Shelly. If you have a climate that does not require an AC in the evening then you might want to use an electric fan. And during daytime, try to open your windows and let the air come in or try switching the AC on and time it. This will actually help you minimize the usage of AC.
james braselton | Aug 4, 2013 11:18 AM
hi there the ac unit will be 8,000 btu ac with a 5 kw generator soo all i need is gas money
Joey | Apr 13, 2015 10:07 AM


I Thank you for posting all these articles comments, and stories I have a less then 800 square foot home and my AC bill has been pretty high even since it was two people and now one the last three years , Im about to install an 10, 800 btu A/C wall unit and turn off the central a/c it wold cost almost 3000 thousand dollars to replace in order to get the same billing, from this post , I thank all the contributors for taking the time to write , cause it sure gives a guy relief  to know , he's headed in the right direction specially  on a budget




Julie Robinson | May 29, 2016 7:06 PM

I have recently moved from a place with central air. Summer months were outrageous. In the new place we just installed two units soon to be three. The only concern have is that they are slightly older. I'm concerned this may in fact effect cost. I find comfort in reading other posted comments in central verse unit but still question the age of the units. Anyone have anything to offer?

Paul | May 29, 2016 7:27 PM


Check the EER rating of your window AC units.  If there is no sticker lookup the model online to get that information.  Most newer window units from what I have seen don't get much higher than an EER of 11.  We upgraded our old central AIR unit from a 10 SEER to a 16 SEER, and our enegy bills dropped almost in half.  If your new home is small, then windows units can work great, just make sure you insulate around the units really well.  use tape and expanding foam to prevent any thermal leaks.  I still have my window units in storage.  As they are great in case you have a power outage and need to keep your home cool off a generator or large UPS.

Julie | May 29, 2016 7:36 PM

Thanks Paul! I'm not sure where I'd find the ratings  as most of the units are worn. The one is a 1998 8000 but Fedders this i know from picture match. The space is not very huge but not tiny. For now  I have one in bedroom in hallway and one in living room. I've closed off other bed and chocked the bottom of the door until the other is installed. All other rooms are sealed and the house has  cooled down in 35 minutes. I'm now thinking I've  been over thinking and it may be OK! :) Thanks!!!


Joey | May 29, 2016 8:20 PM

Same guy who posted last year well with 752 square ft my unit cools entire house freezing with 10, 800 btu unit never turn it off only in the morning  cause it's too cold , and in winter I didn't use it I spent about 75, a month for ac on alll day and night and in winter 42 entire bill


I just bought a new one LG with yje the on off timer 12 seer I plan to save even more 

Paul | May 29, 2016 8:27 PM

Thats inspiring News Joey!  what kind of KWH rates do you pay where you are located?  I am at about 8.5 Cents / KWH in Houston.

Ralph | Jun 24, 2016 9:05 PM

Trying to decide whether to go with my BIG swamp cooler or try to find a small high EER A/C unit. I'm off grid in NorCal and my little swamp cooler that I've had for the past 20 years died from water pump issues. I have 4 100w panels (upgradeable to 6) and am currently pulling in about 275-300 amp hours per day. I hope to have enough to run both whichever cooling unit I go with as well as my internet connection as well as my pc or laptop.


Note to those going with the attic fans: My folks had one installed in the attic of their place in Pasadena with a temp. switch set to turn it on at 100°. It worked fine from 1976, when it was installed, till 1993, when the bearings packed it in and it started a fire that pretty much burnt the house down.


Luckily, Mom was back visiting kinfolk in North Carolina when it happened...

Chris | Aug 25, 2016 8:50 AM

Hello, we have been using a 8000 but unit in our living room for about 4 years now. We have an older home unit that needs replacement, and with the housing market being so volatile and money being so tight (mother retired on a small pention) we decided to install a window unit because I work during the day, and my mother spends most of her time in the kitchen/ living room. Added 2 more to each bedroom and Electricity bill has been under $200 even during summer. We live in Florida as well, so that is impressive to stay below $200. I noticed a few months back that both of our adjacent neighbors have adopted our idea. These comments are great proof that this really does work. Thank you everyone!

Tim Johnson | Oct 7, 2016 5:12 PM

Just wanted to provide an update on window acs.  Most (mid 2016) are around 12 eer(most use ceer ratings which isn't directly compatible with seer or eer, but you can still calculate eer by dividing BTUs per hour by watts) right now and the highest I've found is 12.4 eer for some new ge and Chinese models.  This is roughly equivalent to about 14.2 seer for a central unit.  What that means is that they're essentially on par with central AC efficiency and could be quite better once you account for duct losses which are commonly upwards of 20%.  It's a myth that they are less efficient.  Furthermore,  because they're so cheap it's easy to zone your house like Paul did and replace them in a couple years with more efficient models as they come out rather than being stuck with a big expensive monolithic system.   I haven't found any with ECM fans yet like mini splits and efficient air handlers use.  I think those will boost eer even higher in the coming years.  There are a few connected window acs now, but they mostly only support proprietary apps.  I expect soon we'll see ones that support more common home automation protocols so it will be trivial to program them to sync with whole house fans and based off other complex schedules, room occupancy and weather conditions.

Point being that there's almost no economic reason I can find to use central AC.    Maybe use central AC because it's quieter and doesn't block windows, but not because it's cheaper.

Great article Paul.

Paul | Oct 7, 2016 5:29 PM


really it comes down to astetics.  Some people don't want a dozen window AC units sticking out of their house.  We upgraded our home AC system with a 16 SEER, and our electric bill is under $100 most months.  Since then I haven't put our window units back in.  But of course our new AC system cost about $6k.  $150 window unit is hard to compete with price wise.  

Sheryl | Mar 4, 2017 7:57 PM

I have a question. For a two bedroom apartment that is connected to the living room and kitchen by a long hall, would I be better off with 5000 btu units in each bedroom and one in the living room than trying to cool the whole thing with one 12,000 btu unit.  I found brand new 5,000 btu units for $99 with free shipping on Amazon and they are rated very high Energy Efficiency.  Thanks.

Kay Potter | Jun 15, 2017 3:40 AM

If my 5000btu is on at night and compressor does not kick in does it use as much electricity as if I left it on fan

Paul | Jun 15, 2017 9:56 AM


Yes if your leave it on and the compressor never runs, that is no different than the fan setting.  Same amount of electricity is used.  

Tim Johnson | Jun 15, 2017 9:56 AM


Generally the smaller ones would be better.  There's no gain in efficiency going bigger plus you can zone temps with the smaller ones and control area temps more precisely.  Only downside is you're now blocking three windows.


Depending on your unit the fan uses between 20 and 90w when running.  I'd guess towards the smaller number.   So, basically having it run continuously not in the eco setting doesn't use very much energy at all as long as the compressor isn't kicking on.     And without the compressor on it's equivalent to the fan only setting wrt wattage and current draw.


Sheryl Donnell | Jun 16, 2017 1:44 AM

Tim Johnson, Thank you for your reply. I went ahead and got the smaller units!


clifton | Aug 26, 2017 10:08 AM

Central heat & air..  OR window unit... ( My home is 2000 sq ft )... All Electric.. I have central heat & air....

My electric bill was $2000 in 2014.....I went Solar Power 2015...with four 285 watt panels ( 2 for my electric hot water tank ) & ( 2 for my 1000 watt inverter.. with 4 lithium batteries ) my home runs on solar 90 %.... My electric bill 2016 was $650.... So far this year.. thru August 2017 =  $278...  With a whole house fan and.... ONE WINDOW A/C UNIT.. ( Running on solar )... My  Electric Bill... May = $2.97 /  June = $13.43 / July = $36.48 / August = $28.71....Most 120 volts window units will work on 1000 watt.. TOTAL COST for Solar Power & Batteries = $5500.... Will Recover this cost in about 5 years


carla | Jun 16, 2018 7:38 PM

  I am wondering if I save money by using the low cool vs. the high cool temp and the lTKPFU

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